From dc6e7c6ea0f6666bb521be66dcb00f1d1200f8c2 Mon Sep 17 00:00:00 2001
From: alanbjohnston <alan.b.johnston@gmail.com>
Date: Sat, 6 Apr 2019 10:22:40 -0400
Subject: [PATCH] Create i2c_slave_register_read.ino

---
 arduino/i2c_slave_register_read.ino | 61 +++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 arduino/i2c_slave_register_read.ino

diff --git a/arduino/i2c_slave_register_read.ino b/arduino/i2c_slave_register_read.ino
new file mode 100644
index 00000000..a4890778
--- /dev/null
+++ b/arduino/i2c_slave_register_read.ino
@@ -0,0 +1,61 @@
+#include <Wire.h>
+#define I2C_ADDRESS 0x4B
+#define REGISTER_0 0x00
+#define REGISTER_1 0x01
+#define REGISTER_2 0x02
+#define REGISTER_3 0x03
+
+uint8_t reg; // I2C read register
+unsigned int reg_0_value = 41151;  
+unsigned int reg_1_value = 53124;
+unsigned int reg_2_value = 65535;
+unsigned int reg_3_value = 0;
+
+void setup() {
+
+  Wire.begin(I2C_ADDRESS);
+  Wire.onRequest(requestEvent);
+  Wire.onReceive(receiveEvent);
+  pinMode(LED_BUILTIN, OUTPUT);
+  Serial.begin(9600);           // start serial for output
+  Serial.println();
+  Serial.println("Starting");
+}
+
+void loop() {
+  Serial.println("Waiting for register read");
+  delay(5000);
+}
+
+void receiveEvent(int bytes) {
+  // Read the first byte to determine which register is concerned
+  reg = Wire.read();
+    Serial.print("Read register ");
+    Serial.println(reg);
+}
+
+void requestEvent() {
+  // Read from the register variable to know what to send back
+  digitalWrite(LED_BUILTIN, HIGH);
+  if (reg == REGISTER_0) {
+    Wire.write((uint8_t *)&reg_0_value, sizeof(reg_0_value));
+    Serial.print("Writing value ");
+    Serial.println(reg_0_value);
+  } else if (reg == REGISTER_1) {
+    Wire.write((uint8_t *)&reg_1_value, sizeof(reg_1_value));
+    Serial.print("Writing value ");
+    Serial.println(reg_1_value);
+  } else if (reg == REGISTER_2) {
+    Wire.write((uint8_t *)&reg_2_value, sizeof(reg_2_value));
+    Serial.print("Writing value ");
+    Serial.println(reg_2_value);
+  } else if (reg == REGISTER_3) {
+    Wire.write((uint8_t *)&reg_3_value, sizeof(reg_3_value));
+    Serial.print("Writing value ");
+    Serial.println(reg_3_value);
+  } else {
+    Serial.println("Unknown register");
+  }
+  delay(50);
+  digitalWrite(LED_BUILTIN, LOW);
+}